Method and apparatus for producing a knitted fabric with projecting barbs

ABSTRACT

A knitted fabric consisting of a base fabric into which while being knitted a supplementary monofilament thread of a thermoplastic material is knitted so as to form loops which are drawn out to a considerable length and are then set by a heat treatment and erected to an upright position relative to the base fabric either by stretching the latter or by means of special hook-shaped tools around which these loops are layed, whereupon these set and erected loops are fixed by a sizing material and are then cut open to form barbs with narrow heads which, when the entire fabric is pressed together with another pile fabric, become hooked together with this other fabric.

[451 Nov. 5, 1974 United States Patent [191 Waller minimum 5mm 33345641 SHEET 02 F 16 Pmmfmv 51914 sum naar 16 PMENTEm 5am 1 sum as BF 15 Mmmm sim 3.845.641

suffix 1suf16 @Mun-Hummm? Q 0 0 0 0 C l Q 0 O O I Q I 0 C METHOD AND APPARATUS Fon rizouucrNG A KNITTED FAluc wml PROJECTING BARBS one4 face or the base fabric which'may penetrate into and be hooked together with the uncut pile of another fabric when the two fabrics are applied face-on-face upon each other, and may be severed from the uncut pile of the second fabric when the two fabrics are ripped with such a force off each other that the barbs will be unbent.

The only textile with such projecting barbs which prior to this invention prooved satisfactory in actual practice were made by weaving. While such a fabric is being woven of a thread of a thermoplastic material, the plush loops are formed by means of metal wires and are thereafter set and cut open to form barbs. These known woven fabrics with projecting barbs have, however, the disadvantage that their production is rela tively expensive and that the finished fabric is nonelastc and relatively stiff and also of a considerable thickness and that therefore this fabric can be employed only for certain types of garments or other articles.

These disadvantages of woven fabrics with projecting barbs rendered it desirable to employ a conventional knitted fabric and to knit monofilament threads of a thermoplastic material into this fabric so as to form plush loops which when set and cut open will form barbs. Such a knitted fabric with projecting barbs will, however, not form a satisfactory fastener element since the monofilament threads when being bent in the normal knitting operation will form loops the closed curved ends of which from which the barbs are made have a relatively large radius of curvature and therefore a width which amounts to about 7 percent of the length of these loops. Due to this large radius of the parts of the plush loops from which the barbs are made on one fabric, these barbs will not-properly penetrate into the uncut pile ofthe other fabric which is tobe fastened together with the first fabric. lf, however, one or another of these barbs should penetrate into and be hooked together with the uncut pile of the other fabric, this barb may be bent open 'by a relatively vsmall force because of its large radius of curvature. Furthermore, the plush loops of the known kinds of knitted plush fabrics do not stand upright from the surface of the base fabric but extend at an acute angle thereto. Only if these lo'ops are very close adjacent to each other, they will be held in a more upright position because they cannot lie down.

However, a fabric with such closely adjacent loops` which are cut so as to form barbs is very inefficient as a fastener since the individual barbs will rarely penetrate into the uncut pile of the second fabric. If the loops are not as close to each other and are in an inclined position. the latter will be pressed back against the base of the first fabric when the two fabrics are pressed against each other and therefore most of the babs will not enter and be hooked together with the uncut pile ofthe second fabric.

lt is an object of the present invention to provide a knittedrfsbri with timatdlyrteissting barbs which.

2 when applied upon a fabric with an uncut pile will be fastened together with the latter at least as securely as if these fabrics were woven, but has the advantages of a knitted fabric of vbeing more quickly produced than a woven fabric andof being elastic at least in one direction.

According to the present invention this object may be attained by providing theplush loops when set in the form of long-drawn loops which are erected to an upright position and the heads of which are drawn to a narrow width and therefore have a small radius so that after being cut open, they form the desired barbs. These narrow barbs of the first fabric may then easily penetrate into and be hooked together with the uncut pile of the second fabric. These barbs which are formed by the narrow heads have the further advantage that,

because of the small radius of curvature of the heads, it requires a much greater force to unbend the hooks than that which would be required if the loops have the normal width and are not long-drawn as in a normal plush fabric. Therefore, the barbs on one fabric which are hooked together with the uncut pile of the other fabric insure that the two fabrics will be very securely fastened to each other. Since they are formed by upwardly projecting plush loops, the barbs will reliably engage into the uncut pile of the second fabric.

The knitted fabric according to the invention may be produced by several different methods.

One of these methods which forms another feature of the invention consists of the steps of combining a knitted one-face base fabric with a supplemental knitted part which consists of monofilament thermoplastic threads and forms long-drawn loops, so that both fabric parts together form a wavy shape, of then stretching this wavy material in the longitudinal direction of the wales and simultaneously setting the stretched long loops, of then exposing the heads of the long-drawn loops by a special procedure, and after they have been erected to form plush loops by an additional stretching operation and a simultaneous dressing with a sizing material, then cutting open these loops so as vto form barbs.

This new method may be carried out on a knitting machine which is provided with two needle systems or on a warp knitting machine which is provided with two needle bars.

Another method of knitting the fabric according to the invention consists in knitting the looped fabric in such a manner by means of a warp knitting machine which is provided with only one needle bar that the weft parts of the combined pillar-stitch and weft insertion are layed around loop holders of the machine which are providedl for forming long-drawn loops and are located outside of the row of needles and act during the period in which several courses are knitted, and that while the loop holders engage into the long-drawn loops, these loops are set. Therefore, by employing the loop holders which act during the period of knitting several courses, the loops which are drawn out by the loop holders may be set while the fabric is still being knitted.

The-present invention also concerns the development of two different apparatus for carrying out the lastmentioned knitting method. One of these apparatus consists according to the invention in providing a loop holder for each loop which is to be drawn but in the form of a setting hook, and in providing for the space between each pair of adjacent needles an endless row of setting hooks which are guided in such a manner that during the formation of several courses these setting hooks will be taken along by the long-drawn loops so that the distance between the adjacent setting hooks is gradually increased. This produces the result that while the knitting operation proceeds the setting hooks which engage into the long-drawn loops will move for a certain length of time along with the base fabric so that during this period those loops may be set which have been drawn out by the setting hooks. This apparatus may be mounted in a very simple manner on any knitting machine of a conventional type.

The second apparatus according to the invention for carrying out the last-mentioned knitting method is provided with loop holders in the form of flat metal parts or lancets which are held by the long-drawn loops of the knitted fabric within a row between two adjacent walescof the base fabric and each of which, in turn, extends within a plane which is directed vertical to the base fabric between two adjacent needles of the needle bar. This apparatus is further provided with two lancet holding devices which alternate in acting on the lancets and the first of which engages with the upper ends of the lancets and embraces them laterally and also holds them in vertical directions when the old loops are being knocked over, while the second holding device which is located underneath the first device serves for holding the lancets laterally during the remainder of the time. This apparatus may likewise be easily mounted on any conventional knitting machine. By providing the first device which holds the lancets while the old loops are being knocked over by engaging with their upper ends and also embracing them laterally, the lancets which are held by the surrounding loops are prevented from being pulled downwardly by the base fabric when the latter moves downwardly while the loops are knocked over. The second holding device which is located underneath this first holding device and alternately to the latter engages with the lancets for holding the same in lateral directions during the remainder of the time is provided for permitting each weft part, which is looped around a lancet above the first holding device for forming a long-drawn loop, to slip downwardly past both lancet holding devices. Therefore, both lancet holding devices together prevent any movement of the lancet.

The features and advantages of the present invention will become more clearly apparent from the following detailed description thereof which is to be read with reference to the accompanying drawings, in which FIG. l shows a pattern for knitting a fabric from which by the removal ofa thread the latter will be converted in accordance with the invention;

FIG. 2 shows diagrammatically a loop formation of the knitted fabric which is produced in accordance with the pattern as shown in FIG. 1;

FIG. 3 shows a diagrammatically simplified cross section which is taken along the wales of the fabric as shown in FIG. 2;

FIG. 4 shows a cross section similar to to FIG. 3 of the fabtic as shown in FIG. movable threads have been removed;

FIG. shows a pattern for knitting a fabric from which by the removal of certain threads another fabric may be produced in accordance with the invention;

that according 2 after the re- FIG. 5A is a schematic simplified view of a knitted fabric produced in accordance with the pattern of FIG.

FIGS. 6 and 7 show two patterns for producing knit ted fabrics in accordance with two further embodiments of the invention in which weft parts of a combined pillar-stitch and weft insertion are layed around and held by loop holders for forming long-drawn loops for producing the barbs;

FIGS. 6A and 7A are respectively schematic simplified views of a knitted fabric produced in accordance with the patterns of FIGS. 6 and 7;

FIG. 8 shows diagrammatically and partly broken away and in section a perspective view of a mechanism which is to be employed with a warp knitting machine for knitting a fabric in accordance with the patterns as shown in FIG. 6 and FIG. 7;

FIG. 9 shows a perspective view of some of the elements of the mechanism as shown in FIG. 8;

FIG. 10 shows, partly broken away, a side view of the mechanism according to FIG. 8; j

FIG. 11 shows, partly broken away and in section, an enlarged side view of a part of the mechanism as shown in FIG. 8;

FIG. l2 shows a cross section which is taken along the line XII-XII of FIG. 1l;

FIG. 13 shows a perspective view of a hook comb of the mechanism according to FIG. 8;

FIG. 14 shows a cross section which is taken along the line XIV XIV of FIG. l0;

FIG. l5 shows a diagrammatic illustration of the mode of operation of the setting hooks of the mechanism according to FIG. 8 during the knitting of the fabric;

FIG. 16 shows diagrammatically simplified and partly in section a side view of a second embodiment of the mechanism for producing the knitted fabric in accordance with the pattern as shown in FIG. 6 or in FIG. 7;

FIG. 17 shows a top view of the mechanism according to FIG. 16;

FIG. 1 8 shows a loop formation of a knitted fabric which is provided with a wavy shape and is produced in accordance with the invention;

FIG. 19 shows a pattern for knitting the fabric as shown in FIG. 18;

FIG. 20 shows a diagrammatically simplified section which is taken along the wales of the fabric as shown in FIG. 18;

FIG. 21 shows a section similar to that as shown in FIG. 20 of a modification of the knitted fabric as shown in FIG. I8;

FIG. 22 shows a section similar to that as shown in FIG. 20 of the knitted fabric which is produced in accordance with the invention from a fabric as shown in FIG. 18;

FIG. 23 shows a modificaton of the loop formation as shown in FIG. 18 for producing a fabric which is likewise provided with upwardly projecting hooks;

FIG. 24 shows a pattern for knitting the fabric as shown in FIG. 23;

FIGS. 25 and 26 show two further patterns produced on a warp knitting machine for knitting two further fabrics from each of which a fabric may be produced which is provided with projecting hooks; and FIG. 26A is a simplified schematic view of a knitted fabric produced in accordance with the pattern of FIG. 26.

In the drawings, FlG. l illustrates a pattern in which the dial needles which are guided in the grooves of the dial of a circular knitting machine are designated by the numeral l, while the cylinder needles which are guided in the grooves of the cylinder are designated by the numeral 2. A firstthread 3 which is of a multifilament type is employed for knitting on the dial needles l a uniform one-face base fabric 4 as shown in FIGS. 3 and 4 which is connected to a supplementary fabric part 5 (FIG. 3) which consists of a second thread 6 which is of a monofilament type and consists of a thermoplastic material, and of a removable .thread 7. Both th-reads 6 and 7 are connected by means of the dial needles to the base fabric 4 and thereby form normal loops 6 and 7 which are disposed within the wales of the base fabric. Thewales of the supplementary fabric part 5 which are formed by means of the cylinder needles 2 are disposed between the adjacent wales of the base fabric, and the second type of thread 6 then forms long-drawn loops 6" which extend over three courses of the base fabric. The successive long-drawn loops 6" of the second thermoplastic type of threads 6 within each wale of the supplementary fabric part 5 are connected to each other by the normal loops 7" of the removable thread 7. This results in the formation of a wavy fabric as may be seen especially in FIG. 3, in which the base fabric 4 forms the wave crests which are curved by the long-drawn loops 6" of the supplementary fabric part 5. FIG. 2 illustrates diagrammatically the loop formation of a knitted fabric which is thus produced and in which the back of the base fabric and the face of the supplementary fabric part may be seen. FIG. 2 also shows very clearly that between two adjacent wales containing long-drawn loops 6" loops 7 are formed on the dial needles l. The loops 7" which are formed of the removable thread 7 reduce the width of the heads of the long-drawn loops 6".

After being thus produced, the fabric is stretched in the longitudinal direction of the wales. This has the result, as shown very clearly in FIG. 3, that the longdrawn loops 6" of the second or thermoplastic type of thread 6 will be stretched and, due to their being tied to the loops 7" of the removable thread 7, especially their heads will be drawn so as to have a rather narrow width which is of great importance for forming the barbs in accordance with the invention. When the long-drawn loops of the second or thermoplastic type of thread are in this stretched position, these threads are set by first being heated and subsequently cooled. Thereafter the removable threads 7 are removed in a manner which is conventional in this art. As may be seen particularly in FIG. 2, this removal of the threads 7 results in the exposure of the heads of the long-drawn loops 6". Due to the fact that the loops of the first kind of thread 3 of the base fabric 4 then engage with the feet of the longdrawn loo s 6", the latter will tend to turn to an upright position, as indicated diagrammatically in FIG. 4.

, For insuring that these loops 6" will be erected to such an upright position, the pile fabric which is thus produced is stretched once more to such an extent that these loops which then form plush loops will be disposed at the desired angles. Thereafter, these loops 6" will be fixed in this upright position by being dressed with a sizing material and will then be cut open at one side so as to form barbs. This cutting operation may be carried out in the manner which is conventional in woven fabrics of this type and therefore does not need to be further described. For increasing the elasticity of the knitted fabric, the base fabric 4 may be composed of two different kinds of first threads 3, one of which is elastic, while the other is nonelastic. The nonelastic threads 3 are then employed for those courses in'which the normal loops 6 of the thermoplastic second kind of thread 6 are formed so that the nonelastic kind of thread 3 of the base fabric 4 will be securely tied together with the thermoplastic barb-forming second kind of thread 6 and the barbs which are formed by the long-drawn loops 6" will thus be firmly anchored in the base fabric 4.

A similar fabric of a wavy shape may also be knitted in accordance with the pattern as shown in FIG. 5 by means of a warp knitting machine which is provided with two needle bars. A base fabric is also produced in this ca'se of a first multifilament kind of thread by means of the needles ll of the first needle bar of the machine. This base fabric comprises a pillar-stitch 13a and a second thread 13b of the same kind which connects two wales to each other..By means of the needles 1l of the first needle bar and the needles 12 of the second needle bar the machine further produces a supplementary fabric part which is composed of threads 16a and 16b of the second monofilament thermoplastic type and of removable threads 17a and 17b. In this supplementary fabric part the longdrawn loops 16" are formed by omitting to lay the threads 16a and 16b around the needles 12 of the second needle bar and by stopping the operation of the second pressure bar. This may also be effected by stopping the operation of the second needle bar which results in the formation of the long-drawn loops. The removable threads 17a and 17b form in either of these cases entirely normal loops which are knitted by the needles 11 of the first needle bar in the form of closed loops into the base fabric and by the needles l2 of the second needle bar in the form of open loops into the supplementary fabric part in which they connect the successive open long-drawn loops to each other which are formed of the threads 16a and 16b of the thermoplastic second kind.

Therefore, a fabric of a wavy shape will also be produced in this case as in the case as illustrated in FIGS. 1 to 4. By then stretching this wavy fabric the longdrawn loops will be stretched once more. These stretched long-drawn loops are then set by being heated and cooled. Thereafter the removable threads 17a and 17b are removed withthe result that the rigid long-drawn loops will turn to an upright position like plush loops. These erected loops are then fixed in the upright position by being dressed with a sizing material and are thereafter cut open at one side so as to form barbs. Instead of employing the same kind of material for the threads 13a and 13b the threads 13a may be made of a nonelastic material, while the threads 13b which connect different wales to each other consist of an elastic material so as to increase the elasticity of the fabric in its transverse direction.

FIGS. 6 and 7 show the patterns of two further fab- 'rics according to the invention which are knitted on a warp knitting machine which has a single needle bar. The base of both of these fabrics consists of two warpthread systems 23a and 23b, the first of which is knitted in a pillar stitch arrangement and the second 

1. A method of producing a knitted one face fabric having courses and wales and on the back face of said fabric upstanding fastener elements being formed by projecting end parts of a multiplicity of cut monofilament threads of a thermoplastic material comprising the steps of knitting a base fabric, knitting at least one monofilament thread of a thermoplastic material into said base fabric so as to form loops on the back side of said base fabric and in said base fabric at least one stitch between each two loops, each of said loops having a pair of foot portions and a head portion, said pairs of foot portions entering into said base fabric in the same course and in two adjacent wales, stretching, heatsetting, and erecting said loops to an erected position so as to form long drawn loops, then dressing said knitted fabric with a sizing material to fix said long drawn loops in said erected position, and then severing at least a part of said long drawn loops to form said fastener elements.
 2. The method as defined in claim 1, comprising the steps of placing said loops of said monofilament threads on the backside of said base fabric around loop holding means for stretching said loops in said erected position, heating said stretched loops and holding them in said stretched condition while a plurality of courses are knitted so that sufficient length of time is attained for heatsetting said stretched loops so as to form said long drawn loops, fixing said long drawn loops in said erected position and severing at least a part of them to form said fastener elements.
 3. The method as defined in claim 2, comprising the steps of knitting said base fabric from at least two warp thread systems one of which knits in a pillar stitch arrangement and the other of which connects different wales to each other, knitting said monofilament threads in said base fabric by forMing a combination of a pillar stitch and weft insertion having weft parts crossing from one wale of said fabric to another, and wale parts extending in each of said wales between said weft parts, connecting the ends of said weft parts to said base fabric only by thread parts of said pillar stitch arrangement of said base fabric which thread parts extend from one course to the next course and connecting each of said wale parts by at least one stitch to said base fabric, winding at least a part of said weft parts of said monofilament threads around said loop holding means for stretching, heatsetting and fixing said long drawn loops in said erected position and severing at least a part of them to enable them to hook into an other fabric.
 4. The method as defined in claim 2, in which said loop holding means are hook shaped and are arranged in endless rows, comprising the steps of moving said loop holding means along predetermined paths together with said long drawn loops during the formation of several courses and holding said loops in this way in an erected stretched condition said sufficient lengths of time for heatsetting them, and fixing them in said erected position.
 5. The method as defined in claim 3, comprising the steps of holding said loop holding means within the spaces between adjacent needles by means of said loops disposed in a row parallel to the row of needles and aligning each of them in a vertical direction perpendicular to the row of needles, so that a plurality of said loops are sliding successively downwardly along each of said loop holding means and are held said sufficient length of time required for heatsetting them, and fixing them in said erected position.
 6. A method of producing a knitted fabric having courses and wales and on one face of said fabric upstanding fastener elements being formed by projecting end parts of a multiplicity of cut monofilament threads of a thermoplastic material, comprising the steps of knitting first on a knitting machine having a first and a second needle system a two-face fabric having wales of stitches on each face by forming stitches on one face by knitting a one face base fabric on said first needle system and by forming stitches on the other face by knitting on said second needle system, at least a part of said stitches of said other face being formed by knitting of said monofilament threads in such a way into said base fabric that said stitches of said monofilament threads extend as elongated stitches over at least one course of said base fabric, each of said elongate stitches having a pair of foot parts and a head part, said foot parts being knitted into said base fabric and each of said head parts being connected with said base fabric by the foot parts of a stitch following in the same wale, stretching said two face fabric in the longitudinal direction of said wales of said two-face fabric so that said elongated stitches are drawn to a long drawn condition, heat setting said elongated stitches in said long drawn condition, releasing said head parts of said elongated stitches from said base fabric to form said long drawn loops by said elongated stitches, stretching said base fabric in the direction of said wales of said base fabric to erect said long drawn loops into erected position, dressing said base fabric with a sizing material to fix said long drawn loops in said erected positions, and severing at least a part of said long drawn loops to form said fastener elements.
 7. The method as defined in claim 6, in which by knitting of said two-face fabric at least one subsequently removable thread is knitted into said two face fabric so as to form stitches on said other side of said two-face fabric to connect each of said head parts of said elongated stitches to said base fabric, and after stretching and heat setting said elongated stitches removing said removable thread so as to release said head parts of said elongated stitches from said base fabric to form said long drawn loops.
 8. The method aS defined in claim 7, in which said two-face fabric is knitted on a circular knitting machine having as said first and second needle systems dial and cylinder needles, respectively, knitting said base fabric by one of said needle systems and said other side of said two-face fabric by the other of said needle systems, connecting said other side of said two-face fabric to said base fabric by said one needle system, and knitting said removable thread for connecting said heads of said elongated stitches to said base fabric at least by said other needle system.
 9. The method as defined in claim 8, in which said removable thread is knitted by said cylinder and dial needles.
 10. The method as defined in claim 7, in which said two-face fabric is knitted on a warp knitting machine having a first and a second needle bar, knitting said base fabric by said first needle bar and knitting alternatively a course of said elongated stitches and a course of said removable thread by said second needle bar and while knitting said elongated stitches periodically omitting the formation of other stitches of said second needle bar while the stitches of said base fabric are further knitted on said first needle bar.
 11. The method as defined in claim 6, in which said other side of said two-face fabric is knitted so that said head parts of said elongated stitches are connected to said base fabric by said foot parts of said elongated stitches of the adjacent course so that all wales of said other face of said two-face fabric are formed only by said elongated stitches, and in which said base fabric is knitted so as to make it extensible, stretching said two-face fabric in said lonitudinal direction of said wales so that said elongated stitches are drawn to a long drawn condition, and eliminating a course of said elongated stitches near the end of said two-face fabric, and than stretching said two-face fabric to such an extent that the head parts of said elongated stitches will be released and erected by untying the connection between all of said elongated stitches within each wale in the same manner as the formation of runs to form said long drawn loops in said erected position.
 12. The method as defined in claim 11, in which said base fabric is made extensible by knitting it longer than said other face of said two-face fabric.
 13. The method as defined in claim 11, in which said base fabric is made extensible by using eleastic threads for those threads of said base fabric which do not connect said elongated stitches to said base fabric. 